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Overview

Stratus functions enable developers to write and execute JavaScript functions in a serverless environment. These functions:

  • Scale horizontally
  • Run in isolated VMs
  • Have web access for external integrations
  • Support complex logic combinations

Functions can interact with external services, allowing you to integrate with your own database, subgraphs, and other services.

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Invocation Types

Schedule

Execute functions on a cron schedule with minimum 1-minute resolution

Webhook

Invoke functions via HTTP POST requests using API keys

Subscription

Trigger functions automatically when subscribed events occur

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Schedule Invocation

While there’s no maximum schedule limit, the minimum resolution is 1 minute. Schedules with smaller intervals will fail.

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Webhook Invocation

To invoke functions via webhook:

  1. Create a Stratus-scoped API key in the admin panel
  2. Use the unique webhook URL assigned to your function
curl --request POST \
  --url https://admin.snagsolutions.io/api/stratus/functions/<functionID>/invoke \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <stratus_api_key>' \
  --data '{
    "organizationId": "org-1234",
    "websiteId": "site-5678",
    "input": {
      "foo": 123,
      "bar": "example value"
    }
  }'

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Subscription Invocation

Functions linked to subscriptions execute automatically when subscription events fire. Unlike webhooks, subscription-based invocations receive a single payload per event.

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Writing Functions

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Basic Structure

All Stratus functions must follow these rules:

1

Export Single Handler

Only one handler function can be exported per file

2

Use Async Function

Handlers must be asynchronous

3

Include Required Parameters

Functions must accept input and output parameters

Basic Template
module.exports.handler = async (input, output) => {
  // Your function logic here
};

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The Output Class

The output parameter provides methods for managing function results and actions:

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setResult
function

Sets the function result data (called once before buildOutput)

setResult(resultObject: Record<string, any>): void
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setError
function

Logs a failure and stops future executions

setError(error: string): void
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addTransaction
function

Adds a transaction to the execution queue (requires relayer connection)

addTransaction(tx: Pick<SendTransactionParameters, 'to' | 'data' | 'value'>): void
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buildOutput
function

Finalizes and returns the function output (required)

buildOutput(): Record<string, any>

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Executing Transactions

To execute transactions, your function must be connected to a relayer in your account.

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Transaction Rules

  • Maximum 500 transactions per function run
  • Transactions execute in the order they’re added
  • All transactions use the connected relayer

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Approved Modules

Only pre-approved npm modules can be used in Stratus functions. Contact Snag Solutions if you need additional modules.

Currently approved modules:

  • axios
  • lodash
  • viem
  • ioRedis

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Example Function

const axios = require('axios');

module.exports.handler = async (input, output) => {
  try {
    // Make an external API call
    const response = await axios.get('https://api.example.com/data');
    
    // Set the result
    output.setResult({ 
      data: response.data,
      timestamp: Date.now()
    });

    // Add a transaction if needed
    output.addTransaction({
      to: '0x123...',
      data: '0x456...',
      value: '0'
    });

    // Return the built output
    return output.buildOutput();
  } catch (error) {
    output.setError(`Function failed: ${error.message}`);
    return output.buildOutput();
  }
};

Need Additional Modules?

Contact Snag Solutions if you need access to additional npm modules for your Stratus functions.

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